The migration of histone core particles in chromatin will be studied. First, we will briefly re-investigate the small conformational changes observed in H-1 depleted olibonucleosomes under conditions where migration is known to occur, and assess the effects (if any) of histone crosslinking on these changes. The main body of the research, however, will be centered on development of a quantitative assay for core migration. In brief, this assay involves the use of a rat satellite I nucleosome, for which two positions on the sequenced DNA are quite precisely known. This will be ligated to a companion histone-free fragment. The presence of a Hind III site at the juncture will allow precise determination of the spectrum of core locations following migration. Migration will be studied as a function of ionic strength, temperature, the presence or absence of H1, and modification of the core. Modifications will include crosslinking, histone acetylation, and the addition of HMG proteins. Finally, an attempt will be made to see if transcription of yeast oligonucleosomes can "drive" cores onto linked satellite DNA fragments. It is hoped that this research will help elucidate the mechanism of transcription in eukaryotes.